The issue is, when we are executing this command in our Production environment, it returns the exit code as Null even though the data loaded successfully into the table.
But it should return the exit code as 0. Whereas in our QA environment, we executed with same csv file and same code and its returning the exit code as 0 which is correct.
(The control file and )

As its seems to be environment issue, we rebooted our server and did everything but still we are getting the same issue. (exit code as null)
We should get the exit code as zero.

I'm not sure this is really a PowerShell problem; PowerShell just captures whatever code is returned by the external executable. Have you tested the return code in your production environment by manually running the command, versus calling it from PowerShell?